Embedded Systems Simplify HMI

If the machine you build needs a graphical operator interface, there's finally a middle ground between a full-blown Windows PC and a proprietary operator interface platform. Vendors are offering an entirely new class of operator interface products based on compact, embedded operating systems such as Windows CE, Windows NT Embedded, and Windows XP Embedded.

These products combine the low cost and compact footprint of a proprietary operator interface with the connectivity and familiarity of a standard operating system (OS). These OIs sound like the best of both worlds and they can be, if used in the right applications. However, industrial OEMs cannot successfully deploy a compact embedded OS without a basic understanding of embedded systems technology.

PCs running Windows desktop operating systems such as NT and XP are sold with the OS installed, but without any operator interface application software. The OEM is expected to purchase the PC, then purchase and install an operator interface application.

Proprietary operator interface devices are sold with both an OS and an operator interface application installed. Both the OS and the application software are proprietary, and modification to either is typically impossible or impractical. The machine builder is expected to know the application well enough to specify, purchase, and configure the right proprietary interface.

Operator interface devices based on embedded operating systems are sold like proprietary operator interface devices with the OS and the application both installed. This is because the vendor must customize the embedded OS prior to installation of application software. A detailed explanation of embedded OS deployment can be found at

Once a customized embedded OS is created and downloaded to the hardware platform by the vendor, the vendor downloads the operator interface application software to create the final product.

What does this mean to an industrial OEM contemplating the purchase of an operator interface product based on an embedded OS? It means that specification of an operator interface using an embedded OS is much like the procedure required to purchase a proprietary operator interface device. The machine builder must know the application, and must purchase the operator interface device based on this knowledge. As with a proprietary operator interface device, modifications after purchase are impossible or impractical.

If the specification process is so rigorous, then why would an OEM want to purchase an operator interface based on an embedded OS? When compared to a desktop Windows PC, an operator interface with an embedded OS is cheaper, smaller, and more reliable. In many cases, the hard disk can be eliminated along with cooling fans.

From an industrial OEM perspective, an operator interface with an embedded OS is similar to a proprietary operator interface, but it is much less expensive for a vendor to develop and deploy. This cheaper development process means vendors can offer embedded OS operator interfaces with many more features than comparable proprietary products.

For example, many OEMs want their OI to be web-enabled. This capability can be easily included in an embedded product, but it would be very expensive for a vendor to include it in a proprietary product. Eaton Cutler-Hammer's (

According to Clyde Thomas, product line manager with Cutler-Hammer, NT Embedded lets ePro integrate web-based technologies. "OEMs can use the built-in web browser to deliver content such as operating or machine maintenance procedures to the operator," explains Thomas. "These procedures can be located on a web server without the need to have this information stored locally on each operator interface unit."

Xycom Automation offers an extensive line of operator interface products based on Windows CE. Several are bundled with InduSoft Web Studio OI software. "CE computing resource requirements are minimal, so our units have no hard drive, are low power, and don't need a cooling fan," says Damato. "CE allows us to easily incorporate advanced features such as a USB port, Ethernet communications, and a Windows interface."

Rockwell Automation (

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